1. Field of the Invention
This invention relates to an instrument for tightening elongated wound closure elements around body tissue and, in particular, for tightening wound closure elements around the human sternum following surgery.
2. Background of the Related Art
Sternum repair may be required as a result of either cardiac surgery or direct injury to the sternum. In order to perform various cardiac surgical procedures, the sternum must first be halved to permit access to the heart, and then rejoined upon completion of the primary surgical procedure. The need for ensuring tight and secure closure of a wound closure element in any situation cannot be overstated, particularly when the closure element is designed for closing the human sternum. Insufficient sternum closure following surgery not only prohibits osteosynthesis, but also can cause dangerous sternum infection.
Presently, there are many known products for repairing the sternum and/or human body tissue in areas where a repair may be required either as a result of injury or a surgical procedure. Such wound closure products can include wires, sutures, ribbons or widened and elongated straps which are wrapped around the body part to be repaired. These wound closure products can be manufactured from a variety of materials including surgical gut, silk, cotton, or a polyolefin such as polypropylene, polyamide, polyglycolic acids, and polyesters such as polyethylene, terepthalate and glycolide-lactide copolymer.
One particular device for sternum closure is the Controlled Tension Osteosynthesis System which was developed by Dr. Josef Vincent and is described in The Annals of Thoracic Surgery, Volume 41, Number 2 (February 1986). This system discloses a stainless steel plate which is mounted across the halved sternum and is anchored by a series of wires placed through or around the sternum. Also disclosed in this system is a device for straining the wire mounted through the anchor plate to the desired tension, where the device then trims the wire to the correct size. While this is a useful system for closing the sternum, there are several disadvantages to using this procedure. One drawback of this procedure is that the wires are difficult to position while another more dangerous drawback is that the wires can injure arteries during their placement in the bone. Another major disadvantage of using wires is that a wire can slice through thin or osteoporotic bone thereby destroying the compression rigidity of the sternal closure.
In order to overcome the drawbacks of the wire sternum closure, elongated straps or ribbons are often utilized. In sternum closure devices which utilize elongated straps or ribbons, such as is disclosed in U.S. Pat. No. 4,813,416 and U.S. Pat. No. 4,201,215, tightening and adjusting the straps is often difficult to perform and requires the use of two hands, one to hold one end of the ribbon stationary and a second hand to adjust, tighten and trim the opposite ribbon end.